It is known that the sidewalls of tires have a large number of markings, such as the manufacturer's mark, the type of tire, the size of the tire, etc. These markings are obtained by providing means that are able to mold these markings, referred to below as “marking means”, on the mold, and more particularly on side parts of this mold that are referred to as “shells”. The shells are rotationally symmetrical parts, generally made of steel, and the patterns or markings to be reproduced on the tires are produced by machining, for example by etching or milling. When these parts are difficult to produce by conventional machining means such as by turning or milling, it is possible to obtain them by using aluminium parts obtained by casting. It is then possible to use a wide variety of patterns to be imprinted.
Tires in which the sidewalls are used for the application of tread pattern elements are also known. For example, document EP 1 560 688 describes a mold for a tire including a plurality of tread sectors for forming the tread, a mold back supporting the mold sectors, and molding shells for the lateral walls, the shells being produced from a single casting model. This mold is used to produce tires having tread pattern elements extending from the tread to the sidewalls. However, this type of design does not make it possible to produce certain types of complex tread pattern. Any change in the design of the tread patterns involves changing the entire mold, this involving high costs.
However, depending on the type of tire to be produced, it may be necessary to change the patterns initially provided.
Document U.S. Pat. No. 4,547,139 discloses the use of removable plates placed in a shell of a mold. These plates have marking means comprising indications which have to be changed regularly, for example the tire manufacturing period. However, because the plate has a relatively small size, the area of the elements it can contain is limited. It is thus not possible to incorporate a significant area of tread pattern elements into the sidewalk. Moreover, fixing the plate in the mold is complex.
Document JP61019314 discloses the use of a removable insert in the form of an annular one-piece part. More particularly, this annular insert is housed in a groove extending in a shell of the mold. This insert then has a relatively large diameter, this requiring great precision in its production in order that it satisfactorily fits in the groove, specifically around the entire circumference of this groove.
Document U.S. Pat. No. 1,632,310 discloses a mold for vulcanizing and molding a tire consisting of a plurality of interchangeable sections that make it possible to mold the sidewall or some other part of the tire. Each section contains molding cavities that form different letters or signs which, when the sections are arranged in a particular manner, make it possible to mold a succession of patterns that have a meaning and make it possible to identify the tires on which they are molded.
There is thus a need to provide a solution for replacing means for molding tread patterns that extend over the sidewalls of a tire which makes it possible to provide a sufficient molding area, while being easier and more practical to realize than in the related art.